1. Field of the Invention
The present invention relates to an electrical connector for electrically connecting an electronic package such as a central processing unit (CPU) with a circuit substrate such as a printed circuit board (PCB), and particularly to a land grid array connector with metal retention arms for stabilizing the CPU.
2. Description of Prior Art
Land grid array (LGA) connectors are commonly used with electronic packages such as CPUs. An LGA connector does not require soldering when it is engaged with an associated printed circuit board (PCB). Normally, an LGA assembly includes an electronic package having a plurality of flat contact pads formed on a bottom surface thereof, a connector having an insulative housing and defining a plurality of passageways arranged in a rectangular array, and a plurality of conductive contacts received in the passageways of the connector for electrically connecting with the electronic package.
In keeping with the trend toward miniaturization in computer technology, LGA connectors have become smaller and smaller while the density of the array of contacts has become higher and higher. In light of this, it is essential to accurately align and then fix the electronic package to the LGA connector to ensure correct electrical connection and reliable signal transmission therebetween. Several means have been devised to this end, and are disclosed in U.S. Pat. Nos. 6,146,152, 6,186,797, 6,164,978, 6,203,331 and 6,179,624.
Referring to FIG. 3, U.S. Pat. No. 6,146,152 discloses an LGA connector comprising an insulative housing 6 defining a plurality of passageways 60 therein for receiving LGA contacts 5. The housing 6 is substantially a parallelepiped having four raised sides 61 cooperatively defining a central cavity 63 therebetween. The central cavity 63 is sized to receive an external electrical device such as a CPU package 7 therein. A multiplicity of passageways 60 is defined in a main body of the housing 6, below and in communication with the central cavity 63. A multiplicity of LGA contacts 5 is received in the passageways 60 respectively. A first resilient arm 611 is formed in one of the four raised sides 61, and can deform into a first space 610 defined in said raised side 61. Two second resilient arms 612 are formed in another raised side 61 that is adjacent said one of the four raised sides 61. The second resilient arms 612 can deform into respective second spaces 620 defined in said other raised side 61. The first resilient arm 611 and the second resilient arms 612 each have a chamfered surface 611A, 612A respectively formed in an upper portion thereof, for cooperatively guiding insertion of the CPU package 7 into the central cavity 63. Thus the CPU package 7 can be fixed in the central cavity 63 by normal force arising from the deformation of the resilient arms 611, 612.
A recessed bottom surface of the housing 6 at the central cavity 63 must be coplanar to ensure accurate receipt of the CPU package 7. The housing 6 is typically made by injection molding. Thus a material of the housing 6 needs to be both insulative and able to flow freely during the molding process. Generally, such material has poor elastic strength and resilient deformation capability. The resilient arms 611, 612 are integrally formed with the housing 6, therefore the resilient arms 611, 612 generally have poor elastic strength and resilient properties. Occasionally, undesired shock and vibration sustained by the CPU package 7 causes the resilient arms 611, 612 to deform improperly or even break. When this happens, the CPU package 7 may become displaced in the central cavity 63. This can result in failure of signal transmission between the CPU package 7 and the LGA connector.
Hence, an new LGA connector that overcomes the above-mentioned difficulties is desired.
Accordingly, an object of the present invention is to provide an electrical connector for electrically connecting an electronic package with a circuit substrate such as a PCB, the electrical connector having resilient retention arms that resist improper deformation and damage.
To achieve the above-mentioned object, an electrical connector for connecting an electronic package with a circuit substrate is provided by the present invention. In a preferred embodiment, the electrical connector is an LGA connector, and includes a parallelepiped-shaped insulative housing and a plurality of retention arms. The housing includes four raised sides, and the retention arms are located in two contiguous raised sides. The retention arms include engaging portions for resiliently abutting side walls of the electronic package. A material of the retention arms is different from a material of the housing. In the preferred embodiment, the material of the retention arms is metal. Thus the retention arms have superior resiliency, especially compared to the material of the housing.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: